A disadvantage of traveling by airline, train, bus or automobile is the inability to stabilize the head while sleeping in an upright or near upright position. In the past, passengers of common carriers, especially airline passengers, could recline their headrest-equipped seats to a point where gravity worked to pull the head back towards the headrest. The only impediment to getting a restful sleep during that era, with respect to movement of the head, was gravity induced side-to-side or lateral movement of the head due to inadequate lateral support. A state of the art solution introduced in the early 1980's and which is still in use today to address this problem is the horseshoe or U-shape inflatable and non-inflatable pillow, U.S. Pat. No. 4,285,081. However, it was not the first solution introduced to the arts to address the problem, U.S. Pat. No. 4,161,946, U.S. Pat. No. 4,183,583, and U.S. Pat. No. 4,232,663 were predecessors but the U-shape pillow was the most practical during this time to address the issue of lateral head movement while sleeping. The U-shape pillow design basically consists of a left lateral pillow section, right lateral pillow section and rear pillow section. The lateral pillow sections were designed to provide lateral support to the head while sleeping in a reclined position. However, this U-shape design is not without disadvantage. The rear pillow section of the state of the art design fits behind the neck along the cervical vertebrae just below the occipital bone of the head. With most body types, the rear pillow section, when filled with air or filler material, tends to extend beyond the occipital bone of the head and the dorsal of the scapula (i.e., shoulder blade). In the reclined position, the rear pillow section generally fills the void between the back of the neck and the backrest and headrest of the reclined seat. Unfortunately because of the inferior design of this rear pillow section, the neck is pushed forward away from the backrest and headrest creating an unnatural curvature in the cervical vertebrae and thereby forwardly displacing the head from the headrest. This unnatural curvature is exacerbated as the reclined position increases. This is because as the head moves farther aft out of the vertical plane, the impact of gravity will increase the force acting on the displaced head pulling it towards the headrest and thus increasing the unnatural curvature of the cervical vertebrae and discomfort in the neck. This interaction does not allow the thoracic vertebrae of the back, the cervical vertebrae of the neck, and the occipital bone of the head to rest in their natural curvature state along the backrest and headrest of the seat. The discomfort felt at the back of the neck, caused by the inferior designed rear pillow section, can be reduced by decreasing the recline-angle, but this reveals yet another problem in the current state of the art U-shape travel pillow that must be addressed and will be introduced in the following paragraph.
The transportation industry, especially the common airline carriers, are under economic pressure to increase revenue by adding more seats to their aircraft fleet to transport more passengers without increase in overall size of their aircraft to accommodate these additional seats. The result has been less room between seats, which translates to a reduction in how far seats can be reclined without encroaching on the leg and personal space of the persons sitting behind. Moreover, the recline-angle is also limited by the viewing angle restrictions for multimedia entertainment systems which are now prominently located in the rear of most seat headrests for servicing the passenger sitting behind. Too high a recline-angle can hinder the ability of the passengers, sitting behind, to view and interface with these multimedia systems. This reduction in seat recline-angle has drastically changed how gravity influences the motion of the human head while sleeping. The problem, once limited to only lateral motion of the head, now has the added dimension of forward motion or drooping of the head. Because travelers are now forced to sleep in a more upright position, than just two decades ago, the probability of forward head movement or drooping has increased. During slight disruptions in momentum of the transport vehicle and/or when unexpected movement of the sleeper occurs, gravity may, because of the reduced recline-angle, pull the head forward causing the sleeper to wake suddenly. It should be stated that when sleeping in a vertical or near-vertical reclined position, the head will naturally droop forward of the shoulder to rest. This natural tendency is not in itself a negative as long as a sleeping pillow supports and maintains the forwardly resting head in, at minimum, a near-vertical position and deters forward motion by stabilizing the head while at rest. The volume of the conventional U-shape pillow is mostly concentrated posteriorly to and laterally to the neck, which makes it ineffectual in supporting and stabilizing a forwardly resting head. When using the current state of the art U-shape travel pillow, this tendency is even more probable because of the more forward position of the head relative to the seat headrest because of the innate forward displacement of the neck and cervical vertebrae caused by the rear pillow section.
An ad hoc solution for remedying this problem would be to reduce the air pressure in the rear pillow section, thereby reducing the overall volume of the rear support section. However, since the inflatable state of the art U-shape design employs a single inflatable bladder or single chamber design, the user cannot adjust the pressure in rear pillow section without affecting the pressure in the lateral pillow sections. To do so would mean a reduction in chamber pressure in the lateral pillow sections making them less supportive. This limitation prevents the user from adjusting the volume or thickness of the rear pillow section to maintain the natural curvature of the user's cervical vertebrae while resting on a headrest equipped seat. For the non-inflatable design, the filler material can be removed from the rear section allowing it to be compressed. However, this approach fundamentally changes the U-shape pillow's design and thus moves into the domain of new matter.
Additionally, the current state of the art U-shape pillow tends to shift position when in use. When sleeping in a vertical or near-vertical reclined position, the head will naturally tilt forward of the shoulder line while at rest.
This creates forces and moments that act forward of the shoulder line requiring the rear pillow section of the current state of the art to carry the force required to counteract and stabilizes these forwardly acting forces and moments. Moreover, because of the posterior position of the pillow's rear section around the neck, the pillow's rear section pulls the neck and head forward away from the headrest and in the process further increases the tendency for forward head drooping, illustrating yet another deficiency in the current state of the art design. Strong neck muscles could resist this forward tendency, but it would require neck muscles to not be at rest, which defeats the purpose of a restful sleep.
Sleepers will sometimes reposition themselves while sleeping causing the current state of the art travel pillow to sometimes slide upward, pivot along, and/or rotate around the sleeper's neck and cervical vertebrae. These undesired motions are caused when the sleeper's resting head creates forces and moments acting on the current state of the art travel pillow. The inside surface that comes into contact with the neck and lower surface that rests on shoulders cannot produce the frictional resistance required to prevent slippage because of the inherent design limitations of the current state of the art.
Lastly, it should be noted that the current state of the art U-shape pillow also does not provide a means for preventing forward head drooping. Short of reclining the seats more, which is no longer an option, there is currently no viable solution for preventing the head from moving forward while sleeping in vertical and near-vertical reclined position, provide optimized lateral support, prevent movement of the sleeping pillow while in operative engagement and maintain proper curvature of the cervical vertebrae. These added challenges must be addressed in a single integrated solution in the next generation of travel pillow if sleepers are to achieve a comfortable sleep while being transported by a common or private carrier.
The need of common airline carriers to add more seats to their aircraft and improve the “travel experience” by installing personal multimedia systems into the headrest of their seats has further reduced how far a typical seat can be reclined and ironically may have compromised the passenger's overall “travel experience” by making it more difficult to sleep because the traveler is now asked to sleep in a more upright position than just a few years ago. It should be noted that common carriers, especially the airlines, have made the effort to make seats more comfortable by providing a seat that provides a means for lateral support while sleeping. Unfortunately, these designs don't provide enough lateral support to prevent lateral movement of the head while sleeping and they do not address the issue of forward head movement. Moreover, in most cases, when sitting in a headrest equipped seat, the rear pillow section of the current state of the art U-shape pillow is a redundant component since the purpose of the headrest is to support the head. As already mentioned, in most cases, the rear pillow section tends to forwardly displace the neck and head hindering the user's ability to comfortably position their head against the headrest.
The performance disadvantages associated with the current state of the art U-shape pillow with respect to the changes in transportation system are as followed:
A disadvantage of the current state of the art U-shape pillow is the absence of a means for preventing forward drooping of head while sleeping in a vertical or near vertical reclined position.
Another disadvantage of the current state of the art U-shape pillow is the size and shape of its rear pillow section, particularly its depth and/or thickness; unfortunately this inferior design pushes the cervical vertebrae forward which increases the tendency for undesired forward drooping of the head and causes an unnatural and uncomfortable curvature in the cervical vertebrae while sleeping in a vertical or near vertical position.
Yet another disadvantage of the current state of the art U-shape pillow is the posterior position of its rear pillow section relative to the cervical vertebrae; when forces and moments from a resting head pull the current state of the art forward on the shoulders, the rear pillow section is forced forward against the cervical vertebrae thereby pulling it forward as well.
An additional disadvantage of the current state of the art U-shape pillow is its upper surface which directly/physically supports the head is not optimally angled to maximize the amount of upper surface area providing direct support to the head while sleeping in the vertical or near-vertical position.
Still an additional disadvantage of the current state of the art U-shape pillow is that the majority of its structure is not forward of the shoulder line but is instead located at the lateral and posterior position relative to the head and therefore is not oriented to adequately support a naturally forward tilting and resting head.
Still yet an additional disadvantage of the current state of the art U-shape pillow is it does not provide frontal support to arrest forward motion of a resting head in a vertical or near-vertical position.
A further disadvantage of the current state of the art U-shape pillow is it does not provide adequate lateral support forward of the shoulder line to arrest lateral and combined lateral-forward motions of a resting head in a vertical or near-vertical position.
Still a further disadvantage of the current state of the art U-shape pillow is different shoulder slopes will affect the angle and position at which the right and left pillow sections will provide support to the head.
Still yet a further disadvantage of the current state of the art U-shape pillow is there is no mechanism for deterring undesired movement around the neck and on the shoulders while sleeping in the vertical or near-vertical position as the sleeper shifts position.
These challenges can be overcome if a means for the traveler were provided that prevents forward movement of the head while sleeping, secures and stabilizes the head laterally while sleeping, does not compromise the natural curvature of cervical vertebrae, allows the head to rests naturally on the headrest of a seat, and does not reorient itself with respect to the sleeper's neck and shoulders as the sleeper adjusts his or her body while sleeping.